JS generates a range of random numbers (four cases)

Preface :

JS does not have a ready-made function to generate a random number of the specified range directly.

But it has a function:math.random () This function can generate a random number of [0,1] .

With it, we can generate random numbers within a specified range.

When it comes to scope, there is a boundary value problem. This includes four scenarios:

1)Min≤r≤max (generally this is more common)

2) Min≤r < Max

3) Min < R≤max

4) Min < R < Max

First, Min≤r≤max

function Randomnumboth (Min,max) {var Range = max-min;                var Rand = Math.random (); var num = Min + math.round (Rand * Range); Rounding return num;}

Second, Min≤r < Max

function Randomnum (Min, Max) {var Range = max-min;                var Rand = Math.random ();  var num = Min + math.floor (Rand * Range); to return num;}

Three, Min < R≤max

function Randomnum (Min, Max) {var Range = max-min;                var Rand = Math.random ();    if (Math.Round (Rand * Range) ==0) {return Min + 1;                 } var num = Min + math.round (Rand * Range); return num;}

IV, min < r < Max

function Randomnum (Min, Max) {var Range = max-min;     var Rand = Math.random ();     if (Math.Round (Rand * Range) ==0) {return Min + 1;         }else if (Math.Round (Rand * Max) ==max) {index++;    return Max-1;                        }else{var num = Min + math.round (Rand * Range)-1;    return num; }}

JS generates a range of random numbers (four cases)